As a temporary work-around you can use a proxy for the i.stack.imgur images. Using http://crossorigin.me/ works in the example below.
var i = new Image();
i.crossOrigin = '';
i.onload = function() {
document.write('Image loaded successfully');
};
i.onerror = function(e) {
document.write('Error loading image');
};
i.src = 'http://crossorigin.me/https://i.sstatic.net/PORPF.jpg';